'A' in the given reaction is

When the hydrogen ion concentration [H$$^+$$] changes by a factor of 1000, the value of pH of the solution __________

Match List I with List II

Choose the correct answer from the options given below :

What is the mass ratio of ethylene glycol ($$\mathrm{C_2H_6O_2}$$, molar mass = 62 g/mol) required for making 500 g of 0.25 molal aqueous solution and 250 mL of 0.25 molar aqueous solution?